Orthopaedic Jobs

TKR: Proximal Tibial Resection       


 - Techique: 
    - preparation and exposure for the proximal tibial cut:
          - hyperflexion of the knee to allows the vessels to fall more posteriorly;
          - curved knee retractors are positioned anterior to mid-coronal plane, so that patella tendon and MCL will not be injured;
          - inadvertent transection of the lateral patellar tendon may occur w/ inadequate retraction during the proximal tibial cut;
          - homan retractor may be placed behind posterior tibia and levered off of distal femur, which allows tibia to be translated anteriorly;  
    - extramedullary guides:
           - depth of the tibial cut  (avoid lowering of the joint line
           - posterior slope:
           - rotation of tibial component:
                  - mechanisms can be used to avoid tendency to internal rotation;
                  - look down on tibial plateau & cutting jig w/ knee in flexion;
                  - face of jig should be parallel to plane of the femoral condyles;
           - plane of resection of the mechanical axis:
                  - after fixing tibial cutting jig in place, gentily flex and extend knee while watching that axis of cutting jig is parallel to axis of rotation of knee;
                  - current techniques involve making tibial cut parallel to the tibial anatomic axis (and cutting distal femur at 5-7 deg to its anatomic axis);
                          - this reduces the probability of inadvertent excessively varus cut and thus the likihood of varus alignment of the limb;
                          - as its easier to cut right angles than 3 deg off right angle & varus error in tibia is most common error w/ significant implicantions, 
                                 most techniques call for resection of upper tibia at 90 deg to its long axis;
                                 - valgus errors are well tolerated while varus errors are not;
                  - original PCA technique involved making the proximal tibia in 3 deg of varus in relation to its longitudinal axis;
                          - this means that distal femoral cut must be approx 9 deg of valgus in relation to anatomic axis of femur to have overall mech axis of 0 deg; 
                  - hazards:
                          -
peroneal nerve:
                                - at the level of tibial bone resection, the common peroneal nerve lies superficial to the lateral head of the gastrocnemius;
                                - mean distance from the bony posterolateral corner of the tibia to the nerve was 1.49 cm, with no distance less than 0.9 cm. 
                                   



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Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Wednesday, May 9, 2012 5:07 pm